Display Device

ABSTRACT

The present invention reduces a connection failure between two conductive layers which are connected with each other via a through hole in a display device and reduces a defect of an orientation film formed on a TFT substrate side in a liquid crystal display device. A display device includes a display panel in which a first conductive layer formed on a surface of a substrate, and a second conductive layer which is formed over the first conductive layer as viewed from a surface of the substrate by way of a thin film layer formed of one insulation film or two or more stacked thin films including one insulation film are electrically connected with each other in an opening portion formed in the thin film layer. Out of opening ends of the opening portion of the thin film layer, an outer periphery of the opening end remote from the surface of the substrate changes a distance from the surface of the substrate one time or more during one turn of the outer periphery.

The present application claims priority from Japanese applicationJP2006-150773 filed on May 31, 2006, the content of which is herebyincorpor ated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device, and more particularlyto a technique which is effectively applicable to through holes formedin a display region of a liquid crystal display device.

2. Description of the Related Art

Convention ally, as a display device which displays a video or an image,there has been known a liquid crystal display device which uses a liquidcrystal display panel sealing a liquid crystal material between a pairof substrates.

In the liquid crystal display panel, one substrate out of a pair ofsubstrates is generally referred to as a TFT substrate, and on a surfaceof a transparent substrate, a plurality of scanning signal lines and aplurality of video signal lines which stereoscopically intersects theplurality of scanning signal lines by way of an insulation layer areformed. Then, a region which is surrounded by two neighboring scanningsignal lines and two neighboring video signal lines corresponds to onepixel region, and a TFT element, a pixel electrode and the like arearranged on each pixel region. Further, another substrate which forms apair with the TFT substrate is generally referred to as a countersubstrate.

When the liquid crystal display panel is, for example, of a drive methodwhich is referred to as a vertical-electric-field method such as a TNmethod or a VA method, a counter electrode (also referred to as a commonelectrode) which faces the pixel electrode of the TFT substrate isarranged on a counter substrate side. Further, in case of a drive methodwhich is referred to as a lateral electric field method such as an IPSmethod, for example, the counter electrode is formed on the TFTsubstrate side.

Further, the pixel electrode of the TFT substrate is electricallyconnected with a source electrode of the TFT element. Here, aone-layered or two-layered insulation film is interposed between thesource electrode and the pixel electrode, and the pixel electrode isconnected with the source electrode at an opening portion referred to asa through hole or a contact hole formed in the insulation film (forexample, see patent document 1 (JP-A-11-326949)).

The TFT substrate and the counter substrate form an orientation film forcontrolling the direction (orientation) of liquid crystal molecules in astate that no potential difference exists between the pixel electrodeand the counter electrode and an arrangement and an inclination of theliquid crystal molecules when the potential difference is generatedbetween the pixel electrode and the counter electrode. The orientationfilm is formed on an interface with a liquid crystal material (a liquidcrystal layer) of each substrate and, for example, is formed by applyingrubbing treatment to a surface of a resin film made of polyimide whichis formed to cover the whole display region constituted of a mass of thepixel regions.

Here, the pixel electrodes of the TFT substrate are formed by forming atransparent conductive film made of ITO on a whole surface of aninsulation layer in which through holes (opening portions) are formedand, thereafter, by etching the conductive film. Here, an etching resistused in etching the conductive film is formed by applying a resistmaterial in a liquid form on the conductive film by printing or coatingand, thereafter, by exposing and developing the resist material.

However, in the liquid crystal display device of recent years, forexample, along with the fining of the pixel region and the increase of anumerical aperture of the pixel region, a hole diameter of a throughhole (opening portion) is decreased. Accordingly, for example, when theresist material in a liquid form is applied by printing or coating, theresist material in a liquid form hardly enters a recessed portion formedin a through hole portion. Accordingly, a defect is formed in thethrough hole portion of the etching resist which is formed by exposureand development and hence, the conductive film (ITO film) of the throughhole portion is removed by etching performed subsequently. As a result,for example, there arises a drawback that a conductive failure isgenerated between the source electrode and the pixel electrode of theTFT substrate.

Further, in case of the TFT substrate, in forming the orientation film,the resin material in a liquid form is applied to the pixel electrode byprinting or coating and, thereafter, the resin material is hardened(cured) by baking. Also in this case, for example, when the holediameter of the through hole (opening portion) for connecting the pixelelectrode with the source electrode is small, the printed resin materialin a liquid form hardly enters the recessed portion formed in thethrough hole portion. Accordingly, there have been drawbacks that finerecessed defects are generated in the orientation film on the TFTsubstrate side, the orientation irregularities occur in the through holeportion, and leaking of light occurs.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide atechnique which can reduce a connection failure between two conductivelayers which are connected with each other via a through hole in adisplay device.

It is another object of the present invention to provide, for example, atechnique which is capable of reducing a connection failure between asource electrode of a TFT element and a pixel electrode which areconnected with each other via a through hole in a liquid crystal displaydevice.

It is another object of the present invention to provide, for example, atechnique which can reduce a defect of an orientation film formed on aTFT substrate side in the liquid crystal display device.

The above-mentioned and other objects and novel features of the presentinvention will become apparent from the description of thisspecification and attached drawings.

To schematically explain the summary of typical inventions amonginventions disclosed in this specification, they are as follows.

A display device of the present invention includes a pair of substrateswhich is formed of a transparent member, a first conductive layer whichis formed on one of the substrates, a second conductive layer which isformed on a liquid crystal side of the first conductive layer by way ofan intermediate layer which includes at least one insulation layer, andan opening portion formed in the intermediate layer, wherein out ofopening ends of the opening portion, an outer periphery of the openingend on the liquid crystal side has a distance thereof from the substratechanged one time or more during one turn of the outer periphery.

Further, a display device of the present invention includes a pair ofsubstrates which is formed of a transparent member, a first conductivelayer which is formed on one of the substrates, a second conductivelayer which is formed on a liquid crystal side of the first conductivelayer by way of an intermediate layer which includes at least oneinsulation layer, and an opening portion formed in the intermediatelayer such that the second conductive layer is exposed, wherein thefirst conductive layer is formed to cover the opening portion, and anopening end of the opening portion is formed such that a distancebetween the opening end on another substrate side and the substrate isset at least in two modes.

In the display device of the present invention, due to thecharacterizing constitution thereof, for example, in forming the secondconductive layer by etching, the resist material in a liquid form whichis applied to the conductive film by printing or coating easily enters arecessed portion formed in the opening portion thus prevent ing a shapedefect of an etching resist. Accordingly, it is possible to prevent aconductive failure between the first conductive film and the secondconductive film in the opening portion.

To change the distance between the outer periphery of the opening endand the surface of the substrate, for example, the opening portion maybe formed such that the outer periphery of the opening end on anothersubstrate side passes through two or more regions which differ in thenumber of layers of thin films which are interposed between the surfaceof the substrate and the second conductive layer.

Here, in the display device of the present invention, provided that theliquid crystal display panel includes the substrate which forms thefirst conductive layer and the second conductive layer which areconnected with each other via the through hole on a surface thereof, anyliquid crystal display panel may be used. Particularly, it is desirableto adopt the liquid crystal display panel which seals a liquid crystalmaterial between a pair of substrates.

The substrate of the liquid crystal display panel forms an orientationfilm on an interface thereof with the liquid crystal material (liquidcrystal layer) and the orientation film is formed by applying a resinmaterial in a liquid form to a surface of the substrate in which arecessed portion is formed by the opening portion (through hole) byprinting or coating. Accordingly, by changing a distance between anouter periphery of the opening end remoter from the surface of thesubstrate in distance and the surface of the substrate, for example, theprinted resin material in a liquid form can easily enter the recessedportion formed in the opening portion thus preventing a shape defect ofthe orientation film.

Further, in the liquid crystal display panel or the like, the substratewhich mounts the first conductive layer and the second conductive layerthereon includes, on the surface thereof, a plurality of scanning signallines, a plurality of video signal lines which stereoscopicallyintersects the plurality of scanning signal lines by way of aninsulation layer, and a TFT element and a pixel electrode which arearranged in each region surrounded by two neighboring scanning signallines and two neighboring video signal lines. Here, the first conductivelayer is a source electrode of the TFT element and the second conductivelayer is the pixel electrode.

Further, in the liquid crystal display panel, the substrate which mountsthe first conductive layer and the second conductive layer thereon mayinclude, on the surface thereof, a plurality of scanning signal lines, aplurality of video signal lines which stereoscopically intersect theplurality of scanning signal lines by way of the insulation layer, and aTFT element and a pixel electrode which are arranged in each regionsurrounded by two neighboring scanning signal lines and two neighboringvideo signal lines, common electrodes which are overlapped with thepixel electrodes in plane between the surface of the first substrate andthe pixel electrodes, and a bridge line which stereoscopicallyintersects one scanning signal line by way of an insulation layer andelectrically connects two common electrodes which are arranged with onescanning signal line sandwiched therebetween. In this case, the numberof combinations of the first conductive layer and the second conductivelayer is two. In one combination, the first conductive layer is formedof a source electrode of the TFT element and the second conductive layeris formed of the pixel electrode. In another combination, the firstconductive layer is formed of the common electrode or a conductive layerwhich is brought into contact with and is electrically connected withthe common electrode, and the second conductive layer is the bridgeline.

Further, in the display panel such as a liquid crystal display panel,for example, the TFT element adopts various constitutions (structures).Besides the above-mentioned combination of the source electrode and thepixel electrode and the combination of the common electrode and thebridge line, other conductive layers may be connected via the openingportion (through hole). Also in such a case, by providing theabove-mentioned constitution to the opening portion, when a material ina liquid form is applied to the second conductive layer by printing orcoating, the printed material in a liquid form can easily enter therecessed portion formed in the opening portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a liquid crystal display panel asviewed from a viewer's side;

FIG. 2 is a schematic cross-section al view taken along a line A-A′ inFIG. 1;

FIG. 3 is a schematic plan view showing a constitution al example of onepixel in a display region of a TFT substrate of the liquid crystaldisplay panel;

FIG. 4 is a schematic cross-section al view taken along a line B-B′ inFIG. 3;

FIG. 5 is a schematic cross-section al view taken along a line C-C′ inFIG. 3;

FIG. 6 is a schematic plan view showing the schematic constitution of athrough hole of an embodiment 1;

FIG. 7 is a schematic cross-section al view taken along a line D-D′ inFIG. 6;

FIG. 8 is a schematic plan view showing the schematic constitution of athrough hole in a convention al TFT substrate;

FIG. 9 is a schematic cross-section al view for explaining a point whichbecomes a drawback in the convention al TFT substrate;

FIG. 10 is a schematic cross-section al view for explaining the mannerof operation and advantageous effects of the through hole in theembodiment 1;

FIG. 11 is a schematic plan view for explaining a first modification ofthe through hole in the embodiment 1;

FIG. 12 is a schematic cross-section al view taken along a line F-F′ inFIG. 11;

FIG. 13 is a schematic plan view for explaining a second modification ofthe through hole in the embodiment 1;

FIG. 14 is a schematic plan view for explaining a third modification ofthe through hole in the embodiment 1;

FIG. 15 is a schematic cross-section al view taken along a line G-G′ inFIG. 14;

FIG. 16 is a schematic plan view for explaining a fourth modification ofthe through hole in the embodiment 1;

FIG. 17 is a schematic cross-section al view for explaining anapplication example of the through hole in the embodiment 1;

FIG. 18 is a schematic plan view showing the schematic constitution ofthe through hole in an embodiment 2;

FIG. 19 is a schematic cross-section al view taken along a line H-H′ inFIG. 18;

FIG. 20 is a schematic plan view showing the schematic constitution ofthe through hole in an embodiment 3;

FIG. 21 is a schematic cross-section al view taken along a line J-J′ inFIG. 20;

FIG. 22 is a schematic plan view showing a state of a glass substrateimmediately before forming the through hole;

FIG. 23 is a schematic cross-section al view taken along a line K-K′ inFIG. 22;

FIG. 24 is a schematic plan view for explaining a modification of astepped-portion forming layer MR;

FIG. 25 is a schematic plan view showing the schematic constitution ofthe through hole in an embodiment 4;

FIG. 26 is a schematic cross-section al view taken along a line L-L′ inFIG. 25;

FIG. 27 is a schematic plan view for explaining a first modification ofa connection portion of the through hole in the embodiment 4;

FIG. 28 is a cross-section al view taken along a line M-M′ in FIG. 29;

FIG. 29 is a schematic plan view for explaining a second modification ofthe through hole in the embodiment 4;

FIG. 30 is a schematic plan view showing the schematic constitution ofthe through hole in an embodiment 5;

FIG. 31 is a schematic cross-section al view taken along a line N-N′ inFIG. 30; and

FIG. 32 is a schematic cross-section al view for explaining amodification of the through hole in the embodiment 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Herein after, the present invention is explained in detail inconjunction with embodiments by reference to the drawings. Here, in alldrawings for explaining the embodiments, parts having identicalfunctions are given same symbols and their repeated explanation isomitted.

FIG. 1 to FIG. 5 are schematic views showing one constitution al exampleof a display panel to which the present invention is applied.

FIG. 1 is a schematic plan view of a liquid crystal display panel asviewed from a viewer's side. FIG. 2 is a schematic cross-section al viewtaken along a line A-A′ in FIG. 1. FIG. 3 is a schematic plan viewshowing a constitution al example of one pixel in a display region of aTFT substrate of the liquid crystal display panel. FIG. 4 is a schematiccross-section al view taken along a line B-B′ in FIG. 3. FIG. 5 is aschematic cross-section al view taken along a line C-C′ in FIG. 3.

The present invention relates to a display device which includes adisplay panel, wherein the display panel mounts two conductive layerswhich are connected to each other by way of a through hole on a surfaceof a substrate. As an example of such a display panel, a liquid crystaldisplay panel is named.

The liquid crystal display panel is, as shown in FIG. 1 and FIG. 2, adisplay panel which seals a liquid crystal material 3 between a pair ofsubstrates 1, 2. Here, the pair of substrates 1, 2 is adhered to eachother using a sealing material 4 which is arranged outside a displayregion DA in an annular shape, and the liquid crystal material 3 issealed in a space surrounded by the pair of substrates 1, 2 and thesealing material 4.

Out of the pair of substrates 1, 2, generally, the substrate 1 having anexternal size thereof larger than an external size of the substrate 2 asviewed from a viewer's side is referred to as a TFT substrate. Althoughthe explanation is omitted in FIG. 1 and FIG. 2, the TFT substrate 1 isconfigured such that a plurality of scanning signal lines and aplurality of video signal lines which stereoscopically intersect theplurality of scanning signal lines by way of an insulation layer areformed on a surface of a transparent substrate such as a glasssubstrate. Further, a region which is surrounded by two neighboringscanning signal lines and two neighboring video signal lines correspondsto one pixel region, and a TFT element, a pixel electrode and the likeare arranged on each pixel region. Further, another substrate 2 whichforms a pair with the TFT substrate 1 is generally referred to as acounter substrate.

When the liquid crystal display panel is, for example, of a drive methodreferred to as a vertical-electric-field method such as a TN method or aVA method, a counter electrode (also referred to as a common electrode)which faces the pixel electrode of the TFT substrate 1 is arranged on acounter substrate 2 side. Further, in case of a drive method which isreferred to as a lateral electric field method such as an IPS method,for example, the counter electrode is formed on the TFT substrate 1side.

Next, a constitution al example of one pixel of a display region DA ofthe liquid crystal display panel is briefly explained in conjunctionwith FIG. 3 to FIG. 5.

In the liquid crystal display panel to which the present invention isapplied, one pixel of the display region DA may adopt any constitutionprovided that two conductive layers such as a source electrode of theTFT element and the pixel electrode, for example, are connected witheach other via a through hole. However, in the embodiment describedherein after, the constitution which adopts the IPS method shown in FIG.3 to FIG. 5 is exemplified.

In the IPS-method liquid crystal display panel, the pixel electrodes andthe counter electrodes (common electrodes) are provided on a TFTsubstrate 1 side. Here, the TFT substrate 1 is configured such that, forexample, as shown in FIG. 3 to FIG. 5, a plurality of scanning signallines GL which extend in the x direction are mounted on a surface of aglass substrate SUB, and a plurality of video signal lines DL whichextend in the y direction by way of a first insulation layer PAS1 andstereoscopically intersect the plurality of scanning signal lines GL areformed on the scanning signal lines GL. Further, a region which issurrounded by two neighboring scanning signal lines GL and twoneighboring video signal lines DL corresponds to one pixel region.

Further, on the surface of the glass substrate SUB, for example, aplanar counter electrode CT is formed for every pixel region. Here, thecounter electrodes CT in the respective pixel regions which are arrangedin the x direction are electrically connected with each other by acommon signal line CL which is arranged parallel to the scanning signalline GL. Further, on a side opposite to the direction along which thecommon signal line CL is formed as viewed from the scanning signal lineGL, a common connection pad CP which is electrically connected with thecounter electrode CT is provided.

Further, on a first insulation layer PAS1, besides the video signallines DL, semiconductor layers, drain electrodes SD1, and sourceelectrodes SD2 are formed. Here, the semiconductor layers are formedusing amorphous silicon (a-Si), for example. The semiconductor layersare constituted of semiconductor layers which have a function of achannel layer SC of the TFT element which is arranged in each pixelregion and the semiconductor layers (not shown in the drawing) whichprevent short-circuiting of the scanning signal line GL and the videosignal line DL in a region where the scanning signal line GL and thevideo signal line DL stereoscopically intersect each other, for example.Here, to the semiconductor layer having the function of the channellayer SC of the TFT element, both of the drain electrode SD1 and thesource electrode SD2 which are connected with the video signal line DLare connected.

Further, on a surface (layer) on which the video signal lines DL and thelike are formed, the pixel electrodes PX are formed by way of a secondinsulation layer PAS2. The pixel electrode PX is an electrode which isformed independently for every pixel region and is electricallyconnected with the source electrode SD2 at an opening portion (throughhole) TH1 which is formed in the second insulation layer PAS2. Further,when the counter electrode CT and the pixel electrode PX are, as shownin FIG. 3 to FIG. 5, arranged in a stacked manner by way of the firstinsulation layer PAS1 and the second insulation layer PAS2, the pixelelectrode PX is formed of a comb-teeth-shaped electrode in which slitsSL are formed.

Further, on the second insulation layer PAS2, besides the pixelelectrode PX, for example, bridge lines BR for electrically connectingtwo counter electrodes CT which are arranged vertically with thescanning signal line GL sandwiched therebetween are provided. Here, thebridge line BR is connected with the common signal line CL and thecommon connection pad CP which are arranged with the scanning signalline GL sandwiched therebetween via through holes TH2, TH3.

Further, on the second insulation layer PAS2, an orientation film 5 isformed such that the orientation film covers the pixel electrodes PX andthe bridge lines BR. Here, although not shown in the drawing, thecounter substrate 2 is arranged to face a surface of the TFT substrate 1on which the orientation film 5 is formed.

Herein after, shapes of the through holes when one pixel has theconstitution shown in FIG. 3 to FIG. 5 are explained.

Embodiment 1

FIG. 6 and FIG. 7 are schematic views showing the schematic constitutionof an essential part of the liquid crystal display panel of theembodiment 1 according to the present invention.

FIG. 6 is a schematic plan view showing the schematic constitution ofthe through hole of the embodiment 1, and FIG. 7 is a schematiccross-section al view taken along a line D-D′ in FIG. 6.

This embodiment 1 focuses on the through hole which connects the sourceelectrode of the TFT element and the pixel electrode and theconstitution al example to which the present invention is applied andthe manner of operation and advantageous effects of the constitution alexample are explained.

When one pixel of the display region DA adopts the constitution shown inFIG. 3 to FIG. 5, by applying the present invention to the connectionportion between the source electrode SD2 of the TFT element and thepixel electrode PX, it is possible to achieve the constitution shown inFIG. 6 and FIG. 7, for example. Here, in a region where the sourceelectrode SD2 and the pixel electrode PX are overlapped with each otherin plane, a stepped-portion forming layer MR is partially formed betweenthe source electrode SD2 and the first insulation layer PAS1. In theembodiment 1, the stepped-portion forming layer MR is formedsimultaneously in a step in which the semiconductor layer such as thechannel layer SC of the TFT element is formed. Further, thestepped-portion forming layer MR is, for example, formed in asemicircular profile as viewed in plane.

Here, the opening portion (through hole) TH1 formed in the secondinsulation layer PAS2 is formed such that an outer periphery AR of anopening end remote from the glass substrate SUB passes a region wherethe stepped-portion forming layer MR is formed and a region where thestepped-portion forming layer MR is not formed. Accordingly, the outerperiphery AR of the opening end of the opening portion TH1 remote fromthe glass substrate SUB is configured such that a region where adistance from a surface of the glass substrate SUB is d1 and a regionwhere a distance from a surface of the glass substrate SUB is d2 existduring one turn of the outer periphery. Here, the outer periphery AR ofthe opening end of the opening portion TH1 remote from the glasssubstrate SUB changes the distance from the surface of the glasssubstrate SUB from d1 to d2 at an intersecting point thereof with anouter periphery of the stepped-portion forming layer MR. The manner ofoperation and advantageous effects attributed to the through hole TH1having such a shape are explained in conjunction with FIG. 8 to FIG. 10.

FIG. 8 is a schematic plan view showing the schematic constitution of athrough hole in a convention al TFT substrate. FIG. 9 is a schematiccross-section al view for explaining a point which becomes a drawback inthe convention al TFT substrate. FIG. 10 is a schematic cross-section alview for explaining the manner of operation and advantageous effects ofthe through hole in the embodiment 1. Here, FIG. 9 is a cross-section alview corresponding to a cross section taken along a line E-E′ in FIG. 8,and FIG. 10 is a cross-section al view corresponding to a cross sectiontaken along a line D-D′ in FIG. 6.

In the convention al TFT substrate, a connecting portion of a sourceelectrode SD2 of a TFT element and a pixel electrode PX is configured asshown in FIG. 8 and FIG. 9, for example, wherein the source electrodeSD2 has a region thereof where the pixel electrode PX is overlapped withthe source electrode SD2 in plane arranged substantially parallel to asurface of the glass substrate SUB. That is, in the convention al TFTsubstrate, with respect to an outer periphery AR of an opening end of anopening portion (through hole) TH1 formed in the second insulation layerPAS2 remote from a glass substrate SUB, a distance from a surface of theglass substrate SUB is set to an approximately fixed value d1 at anypoint on the outer periphery AR.

Accordingly, for example, in a step for forming the pixel electrode PX,when a resist material 7 in a liquid form which is used for forming anetching resist is applied by printing or coating to a transparentconductive film 6 made of ITO for forming the pixel electrode PX, forexample, as shown in FIG. 9, there exists a case in which the resistmaterial 7 in a liquid form does not enter a recessed portion formed bythe through hole TH1. When the etching resist is formed by performingdevelopment and exposure in a state that the resist material 7 does notenter the recessed portion formed by the through hole TH1, the recessedportion which is to be covered with the etching resist in an origin alstate exhibits an exposed state. Accordingly, when the conductive film 6is etched, a portion of the conductive film 6 extending to the recessedportion is removed thus giving rise to a drawback that a conductivefailure occurs between the source electrode SD2 and the pixel electrodePX.

On the other hand, in the TFT substrate 1 of the embodiment 1, when theresist material 7 in a liquid form for forming the etching resist isapplied by printing or coating to the transparent conductive film 6 madeof ITO for forming the pixel electrode PX, out of the outer periphery ARof the opening end of the opening portion (through hole) TH1 formed inthe second insulation layer PAS2 remote from the glass substrate SUB, atthe portion where the distance from the surface of the glass substrateSUB changes from d1 to d2, the resist material 7 in a liquid form caneasily enter the recessed portion formed by the through hole TH1.Accordingly, as shown in FIG. 10, the etching resist can be formed bydevelopment and exposure in a state that the resist material 7 is filledin the recessed portion formed by the through hole TH1 and hence, aconductive failure between the source electrode SD2 and the pixelelectrode PX can be prevented.

Although the explanation using drawings is omitted, in manufacturing theTFT substrate 1, also when the orientation film 5 is formed afterforming the pixel electrode PX, a resin material in a liquid form isapplied by printing or coating. Also in this case, when the through holeTH1 has a shape shown in FIG. 8 and FIG. 9, the printed resin materialin a liquid form hardly enters a recessed portion formed in a throughhole portion thus giving rise to a case in which a defect is generatedin the orientation film 5. On the other hand, by forming the orientationfilm 5 as in the case of the TFT substrate 1 of the embodiment 1, in thesame manner as the above-mentioned resist material in a liquid form, outof an outer periphery AR of the through hole TH1 formed in the secondinsulation layer PAS2 remote from the glass substrate SUB, at a portionwhere a distance from the surface of the glass substrate SUB changesfrom d1 to d2, the resin material in a liquid form can easily enter therecessed portion formed in the through hole portion. Accordingly, it ispossible to prevent the occurrence of a defect in the orientation film5.

Here, in explaining the technical feature of the TFT substrate 1 of theembodiment 1, in an example shown in FIG. 6, between the sourceelectrode SD2 and the first insulation layer PAS1, the stepped-portionforming layer MR having the semicircular profile in a plan view isprovided. However, the profile of the stepped-portion forming layer MRin a plan view is not limited to such a profile and, it is needless tosay that the stepped-portion forming layer MR may have other shapes.

The TFT substrate 1 of the embodiment 1 provides the portion where thedistance from the surface of the glass substrate SUB changes from d1 tod2 during one turn of the outer periphery AR of the opening end of theopening portion (through hole) TH1 formed on the second insulation layerPAS2 remote from the glass substrate SUB and hence, the printed orcoated resist material in a liquid form can easily enter the recessedportion formed in the through hole portion.

That is, an essential point in the TFT substrate 1 of the embodiment 1lies in that the outer periphery AR of the opening end of the openingportion (through hole) TH1 formed on the second insulation layer PAS2remote from the glass substrate SUB includes the portion where thedistance from the surface of the glass substrate SUB changes from d1 tod2 during one turn of the outer periphery AR. Provided that thiscondition is satisfied, the profile of the stepped-portion forming layerMR in a plan view may have any shape.

FIG. 11 is a schematic plan view for explaining a first modification ofthe through hole of the embodiment 1. FIG. 12 is a schematiccross-section al view taken along a line F-F′ in FIG. 11.

In forming the portion where the distance from the surface of the glasssubstrate SUB changes from d1 to d2 on the outer periphery AR of theopening end of through hole TH1 formed in the second insulation layerPAS2 remote from the glass substrate SUB, for example, as shown in FIG.11, a rod-like stepped-portion forming layer MR which is elongated inone direction may be provided. Also in this case, by allowing the outerperiphery AR of the opening end of the through hole TH1 formed in thesecond insulation layer PAS2 remote from the glass substrate SUB to passthrough a region where the stepped-portion forming layer MR isinterposed and a region where the stepped-portion forming layer MR isnot interposed, as shown in FIG. 12, on the outer periphery AR of theopening end of the through hole TH1 formed in the second insulationlayer PAS2 remote from the glass substrate SUB, a region in which thedistance from the surface of the glass substrate SUB is d1 and a regionin which the distance from the surface of the glass substrate SUB is d2exist. Accordingly, in the same manner as the example shown in FIG. 6and FIG. 7, a resist material or a resin material in a liquid form caneasily enter the recessed portion formed in the through hole portion.

FIG. 13 is a schematic plan view for explaining a second modification ofthe through hole in the embodiment 1.

In forming the portion where the distance from the surface of the glasssubstrate SUB changes from d1 to d2 on the outer periphery AR of theopening end of through hole TH1 formed in the second insulation layerPAS2 remote from the glass substrate SUB, for example, a cruciformstepped-portion forming layer MR shown in FIG. 13 may be provided. Alsoin this case, by allowing the outer periphery AR of the opening end ofthe through hole TH1 formed in the second insulation layer PAS2 remotefrom the glass substrate SUB to pass through a region where thestepped-portion forming layer MR is interposed and a region where thestepped-portion forming layer MR is not interposed, the cross-section alstructure taken along a line F-F′ in FIG. 13 is configured as shown inFIG. 12. Accordingly, in the same manner as the example shown in FIG. 6and FIG. 7, a resist material or a resin material in a liquid form caneasily enter the recessed portion formed in the through hole portion.

FIG. 14 is a schematic plan view for explaining a third modification ofthe through hole in the embodiment 1. FIG. 15 is a schematiccross-section al view taken along a line G-G′ in FIG. 14. FIG. 16 is aschematic plan view for explaining a fourth modification of the throughhole in the embodiment 1.

In forming the portion where the distance from the surface of the glasssubstrate SUB changes from d1 to d2 on the outer periphery AR of theopening end of through hole TH1 formed in the second insulation layerPAS2 remote from the glass substrate SUB, for example, island-likestepped-portion forming layers MR shown in FIG. 14 may be provided. Alsoin this case, by allowing the outer periphery AR of the opening end ofthe through hole TH1 formed in the second insulation layer PAS2 remotefrom the glass substrate SUB to pass through a region where thestepped-portion forming layer MR is interposed and a region where thestepped-portion forming layer MR is not interposed, as shown in FIG. 15,on the outer periphery AR of the opening end of the through hole TH1formed in the second insulation layer PAS2 remote from the glasssubstrate SUB, a region in which the distance from the surface of theglass substrate SUB is d1 and a region in which the distance from thesurface of the glass substrate SUB is d2 exist. Accordingly, in the samemanner as the example shown in FIG. 6 and FIG. 7, a resist material or aresin material in a liquid form can easily enter the recessed portionformed in the through hole portion.

Further, in the modification shown in FIG. 14, the example in which twoisland-like stepped-portion forming layers MR are formed is exemplified.However, it is needless to say that the present invention is not limitedto such an example and, for example, four island-like stepped-portionforming layers MR may be provided as shown in FIG. 16.

FIG. 17 is a schematic cross-section al view for explaining anapplication example of the through hole in the embodiment 1. Here, FIG.17 is a cross-section al view corresponding to a cross section takenalong a line D-D′ in FIG. 6.

In the TFT substrate of the embodiment 1, to form the portion where thedistance from the surface of the glass substrate SUB changes from d1 tod2 on the outer periphery AR of the opening end of the through hole TH1formed in the second insulation layer PAS2 remote from the glasssubstrate SUB, for example, as shown in FIG. 7, the stepped-portionforming layer MR is provided between the source electrode SD2 and thefirst insulation layer PAS1. However, the formation of thestepped-portion forming layer MR is not limited to such an example and,for example, as shown in FIG. 17, the stepped-portion forming layer MRmay be provided between the first insulation layer PAS1 and the glasssubstrate SUB. In this case, the stepped-portion forming layer MR may besimultaneously formed in a step which forms the scanning signal linesGL, for example. Further, in case of the TFT substrate in which onepixel adopts the constitution shown in FIG. 3 to FIG. 5, for example,there may be a case that a conductive film (ITO film) for forming thecounter electrodes CT and a conductive film (Al film) for forming thescanning signal lines GL and the like are collectively formed. In such acase, the stepped-portion forming layer MR may be constituted bystacking the ITO film and the Al film.

Also in this case, by forming the through hole TH1 in the secondinsulation layer PAS2 such that the outer periphery AR of the openingend remote from the glass substrate SUB passes a region where thestepped-portion forming layer MR is provided and the region where thestepped-portion forming layer MR is not provided, on the outer peripheryAR of the opening end of the through hole TH1 remote from the glasssubstrate SUB, there exists the portion in which the distance from thesurface of the glass substrate SUB changes from d1 to d3 exists duringone turn of the outer periphery AR. Accordingly, in the same manner asthe example shown in FIG. 6 and FIG. 7, a resist material or a resinmaterial in a liquid form can easily enter the recessed portion formedin the through hole portion.

Embodiment 2

FIG. 18 and FIG. 19 are schematic views showing the schematicconstitution of an essential part of a liquid crystal display panel ofan embodiment 2 according to the present invention.

FIG. 18 is a schematic plan view showing the schematic constitution of athrough hole in the embodiment 2. FIG. 19 is a schematic cross-sectional view taken along a line H-H′ in FIG. 18.

In the embodiment 1, by focusing on the through hole which connects thesource electrode of the TFT element and the pixel electrode, as theconstitution al example to which the present invention is applied, thecase which provides the stepped-portion forming layer MR is exemplified.Further, by allowing the outer periphery AR of the opening end of thethrough hole (opening hole) TH1 formed in the second insulation layerPAS2 remote from the glass substrate SUB to pass through the regionwhere the stepped-portion forming layer MR is provided and the regionwhere the stepped-portion forming layer MR is not provided, the portionwhere the distance from the surface of the glass substrate SUB changesfrom d1 to d2 is formed on the outer periphery AR of the opening end ofthe through hole TH1 remote from the glass substrate SUB.

In the embodiment 2, the explanation is made with respect to a methodfor providing a portion where a distance from a surface of a glasssubstrate SUB changes on an outer periphery AR of an opening end of athrough hole TH1 remote from the glass substrate SUB from a viewpointdifferent from the viewpoint of the embodiment 1.

As the method for forming the portion where the distance from a surfaceof a glass substrate SUB changes from d1 to d2 on the outer periphery ARof the opening end of the through hole TH1 remote from the glasssubstrate SUB without forming the stepped-portion forming layer MR, forexample, as shown in FIG. 18, there exists a method which forms a cutoutportion UC in a region of a source electrode SD2 where a pixel electrodePX is overlapped with the source electrode SD2 in plane.

Here, the cutout portion UC of the source electrode SD2 is formed suchthat the outer periphery AR of the through hole TH1 formed in the secondinsulation layer PAS2 remote from the glass substrate SUB intersects anouter periphery of the source electrode SD2 at the cutout portion UC.Due to such a constitution, the outer periphery AR of the opening end ofthe through hole TH1 formed in the second insulation layer PAS2 remotefrom the glass substrate SUB passes through a region where the sourceelectrode SD2 is formed and a region where the source electrode SD2 isnot formed. Accordingly, on the outer periphery AR of the opening end ofthe through hole TH1 remote from the glass substrate SUB, the portionwhere the distance from the surface of the glass substrate SUB changesfrom d1 to d4 exists during one turn of the outer periphery AR.

In this manner, by forming the portion where the distance from thesurface of the glass substrate SUB changes from d1 to d4 on the outerperiphery AR of the opening end of the through hole TH1 remote from theglass substrate SUB, in the same manner as the case in which thestepped-portion forming layer MR exemplified in the embodiment 1 isformed, at the portion where the distance from the surface of the glasssubstrate SUB changes on the outer periphery AR of the opening end ofthe through hole TH1 remote from the glass substrate SUB, a resistmaterial or a resin material in a liquid form can easily enter arecessed portion formed in the through hole portion. Accordingly, it ispossible to prevent a conductive failure between the source electrodeSD2 and the pixel electrode PX and a defect of an orientation film.

Here, the cutout portion UC of the source electrode SD2 may beconfigured such that the outer periphery AR of the opening end of thethrough hole TH1 formed in the second insulation layer PAS2 remote fromthe glass substrate SUB intersects an outer periphery of the sourceelectrode SD2 in the cutout portion UC. Accordingly, it is needless tosay that a shape of the source electrode SD2 in a plan view is notlimited to the shape shown in FIG. 18 and various shapes are applicableas a planar shape of the source electrode SD2.

Embodiment 3

FIG. 20 and FIG. 21 are schematic views showing the schematicconstitution of an essential part of a liquid crystal display panel ofan embodiment 3 according to the present invention.

FIG. 20 is a schematic plan view showing the schematic constitution of athrough hole in the embodiment 3. FIG. 21 is a schematic cross-sectional view taken along a line J-J′ in FIG. 20.

In the embodiment 1 and the embodiment 2, as one example of the throughhole formed in the TFT substrate 1 of the liquid crystal display panel,the through hole TH1 which connects the source electrode SD2 and thepixel electrode PX is exemplified. However, one pixel adopts the pixelconstitution of the TFT substrate having the constitution shown in FIG.3 to FIG. 5, besides the through hole TH1, the through hole TH2 whichconnects the bridge line BR and the common signal line CL and the likemay be formed, for example.

The embodiment 3 focuses on the through hole TH2 which connects thebridge line BR and the common signal line CL, and a constitution alexample and the manner of operation and advantageous effects of a liquidcrystal display panel when the present invention is applied to theliquid crystal display panel of this embodiment 3 is explained.

Provided that one pixel of the display region DA adopts the pixelconstitution shown in FIG. 3 to FIG. 5, for example, when the presentinvention is applied to a connection portion between the common signalline CL and the bridge line BR, the pixel constitution is configured asshown in FIG. 20 and FIG. 21. Here, in a region where the common signalline CL and the bridge line BR are overlapped with each other in plane,between the first insulation layer PAS1 and the second insulation layerPAS2, stepped-portion forming layers MR are partially formed. In theembodiment 3, the stepped-portion forming layers MR are simultaneouslyformed in a step for forming semiconductor layers such as channel layersSC of TFT elements. Further, the stepped-portion forming layers MR areexposed to an opening side surface of the through hole TH2, for example.

Here, the through hole TH1 is configured such that an outer periphery ARof an opening end of the through hole TH1 remote from a glass substrateSUB passes through a region where the stepped-portion forming layer MRis formed and a region where the stepped-portion forming layer MR is notformed. Accordingly, on the outer periphery AR of the opening end of thethrough hole TH2 remote from the glass substrate SUB, a portion where adistance from the surface of the glass substrate SUB changes from d5 tod6 exists during one turn of the outer periphery AR.

In this manner, by forming the portion where the distance from thesurface of the glass substrate SUB changes from d5 to d6 on the outerperiphery AR of the opening end of the through hole TH2 remote from theglass substrate SUB, in the same manner as the case in which thestepped-portion forming layer MR exemplified in the embodiment 1 isformed, at the portion where the distance from the surface of the glasssubstrate SUB changes on the outer periphery AR of the opening end ofthe through hole TH2 remote from the glass substrate SUB, a resistmaterial or a resin material in a liquid form can easily enter arecessed portion formed in the through hole portion. Accordingly, it ispossible to prevent a conductive failure between the common signal lineCL and the bridge line BR and a defect of an orientation film.

FIG. 22 and FIG. 23 are schematic views for explaining a manufacturingmethod of the through hole of the embodiment 3. FIG. 22 is a schematicplan view showing a state of the glass substrate immediately beforeforming the through hole. FIG. 23 is a schematic cross-section al viewtaken along a line K-K′ in FIG. 22.

In manufacturing the TFT substrate having the through hole TH2 of theconstitution shown in the embodiment 3, a method and steps equal toconvention al methods and steps may be adopted up to a step for formingthe first insulation layer PAS1. Then, in forming the semiconductorlayer such as the channel layer SC of the TFT element on the firstinsulation layer PAS1, for example, as shown in FIG. 22 and FIG. 23, therod-like stepped-portion forming layer MR which is longer than a holediameter of the outer periphery AR of the opening end of the throughhole TH2 remote from the glass substrate SUB formed in a later step issimultaneously formed. Thereafter, the second insulation layer PAS2 isformed in the same manner as the convention al method. As a result, onthe second insulation layer PAS2, as shown in FIG. 23, a stepped portionis formed in a boundary between the region where the stepped-portionforming layer MR is formed and the region where the stepped-portionforming layer MR is not formed.

Then, by forming the through hole TH2 in a state shown in FIG. 23, thestepped-portion forming layer MR disposed inside the outer periphery ARof the opening end of the through hole TH2 remote from the glasssubstrate SUB is removed, and the stepped-portion forming layer MRremaining outside the outer periphery AR of the opening end is exposedto the side surface of the through hole TH2. Thereafter, by forming thepixel electrode PX and the bridge line BR in the same manner as theconvention al method, as shown in FIG. 21, it is possible to form theportion where the distance from the surface of the glass substrate SUBchanges from d5 to d6 on the outer periphery AR of the opening end ofthe through hole TH2 remote from the glass substrate SUB.

FIG. 24 is a schematic plan view for explaining a modification of thestepped-portion forming layer MR.

In manufacturing the TFT substrate 1 of the embodiment 3, due to thepresence of the semiconductor layer, when the rod-like stepped-portionforming layer MR is formed as shown in FIG. 22, for example, after theformation of the through hole TH2, the stepped-portion forming layer MRremains in two regions of the outer periphery AR of the opening end ofthe through hole TH2 remote from the glass substrate SUB. However, it isneedless to say that in forming the stepped-portion forming layer MR bythe method used in the embodiment 3, a profile in a plan view of thestepped-portion forming layer MR formed by the semiconductor layer isnot limited to the rod-shape and, for example, the profile may be formedin a cruciform as shown in FIG. 24. In this case, when the through holeTH2 is formed, the stepped-portion forming layers MR remain in fourregion on the outer periphery AR of the opening end of the through holeTH2 remote from the glass substrate SUB.

Here, although the explanation using drawings is omitted, by forming thethrough hole TH3 formed in the connecting portion of the bridge line BRand the common connection pad CP shown in FIG. 3 into a shape(constitution) shown in FIG. 20 and FIG. 21, it is possible to prevent aconductive failure between the common connection pad CP and the bridgeline BR and a defect of an orientation film.

Embodiment 4

FIG. 25 and FIG. 26 are schematic views showing the schematicconstitution of an essential part of a liquid crystal display panel ofan embodiment 4 according to the present invention. FIG. 25 is aschematic plan view showing the schematic constitution of the throughhole in the embodiment 4. FIG. 26 is a schematic cross-section al viewtaken along a line L-L′ in FIG. 25.

In the embodiment 3, by focusing on the through hole TH2 which connectsthe common signal line CL and the bridge line BR, as the constitution alexample to which the present invention is applied, the case whichprovides the stepped-portion forming layer MR is exemplified. Further,by allowing the outer periphery AR of the opening end of the throughhole TH2 remote from the glass substrate SUB to pass through the regionwhere the stepped-portion forming layer MR is provided and the regionwhere the stepped-portion forming layer MR is not provided, the portionwhere the distance from the surface of the glass substrate SUB changesfrom d5 to d6 is formed on the outer periphery AR of the opening end ofthe through hole TH2 remote from the glass substrate SUB.

In the embodiment 4, the explanation is made with respect to a methodwhich forms a portion where a distance from a surface of a glasssubstrate SUB changes on an outer periphery AR of an opening end of athrough hole TH2 remote from the glass substrate SUB from a viewpointdifferent from the viewpoint of the embodiment 3.

As the method for forming the portion where the distance from thesurface of the glass substrate SUB changes on the outer periphery AR ofthe opening end of the through hole TH2 remote from the glass substrateSUB without forming the stepped-portion forming layer MR, for example,as shown in FIG. 25, there exists a method which forms a cutout portionUC in a region of a common signal line CL where a bridge line BR isoverlapped with the common signal line CL.

Here, the cutout portion UC of the common signal line CL is formed suchthat the outer periphery AR of the through hole TH2 remote from theglass substrate SUB intersects an outer periphery of the common signalline CL at the cutout portion UC. Due to such a constitution, the outerperiphery AR of the opening end of the through hole TH2 formed in thefirst insulation layer PAS1 and the second insulation layer PAS2 remotefrom the glass substrate SUB passes through a region where the commonsignal line CL is formed and a region where the common signal line CL isnot formed. Accordingly, on the outer periphery AR of the opening end ofthe through hole TH2 remote from the glass substrate SUB, as shown inFIG. 26, the portion where the distance from the surface of the glasssubstrate SUB changes from d6 to d7 exists during one turn of the outerperiphery AR.

In this manner, by forming the portion where the distance from thesurface of the glass substrate SUB changes from d6 to d7 on the outerperiphery AR of the opening end of the through hole TH2 remote from theglass substrate SUB, in the same manner as the case in which thestepped-portion forming layer MR exemplified in the embodiment 3 isformed, at the portion where the distance from the surface of the glasssubstrate SUB changes on the outer periphery AR of the opening end ofthe through hole TH2 remote from the glass substrate SUB, a resistmaterial or a resin material in a liquid form can easily enter arecessed portion formed in the through hole portion. Accordingly, it ispossible to prevent a conductive failure between the common signal lineCL and the bridge line BR and a defect of an orientation film.

Here, the cutout portion UC of the common signal line CL may beconfigured such that the outer periphery AR of the opening end of thethrough hole TH2 remote from the glass substrate SUB intersects an outerperiphery of the common signal line CL in the cutout portion UC.Accordingly, it is needless to say that a shape of the cutout portion UCin a plan view is not limited to the shape shown in FIG. 25 and variousshapes are applicable as a planar shape of the cutout portion UC.

FIG. 27 is a schematic plan view for explaining a first modification ofthe through hole in the embodiment 4. FIG. 28 is a cross-section al viewtaken along a line M-M′ in FIG. 29. FIG. 30 is a schematic plan view forexplaining a second modification of the through hole in the embodiment4.

The TFT substrate 1 of the embodiment 4 is configured such that onepixel adopts the constitution shown in FIG. 3 to FIG. 5. Here, there maybe a case that counter electrodes CT, scanning signal lines GL, commonsignal lines CL and common connection pads CP which are formed on thesurface of the glass substrate SUB are collectively formed. In thiscase, on the surface of the glass substrate SUB, for example, an ITOfilm for forming the counter electrode CT and conductive films such asan aluminum film for forming the scanning signal lines GL are stackedand, thereafter, the conductive film is etched to form the scanningsignal lines GL and the like. Subsequently, the ITO film is etched toform the counter electrode CT. Accordingly, with respect to the scanningsignal lines GL or the common signal lines CL, there may be a case thatthe ITO film remains below the conductive film such as the aluminumfilm. That is, there may be a case that the ITO film remains between theconductive film and the glass substrate SUB.

In steps for forming the TFT substrate 1 in the embodiment 4, in formingthe cutout portion UC in the common signal line CL, for example, theconductive film formed of an aluminum film and the ITO film may beremoved. However, as shown in FIG. 27 and FIG. 28, it is preferable toform the cutout portion UC by removing the conductive film formed of analuminum film, while leaving an ITO film 8. Due to such a constitution,when the through hole TH2 is formed in the first insulation layer PAS1and the second insulation layer PAS2, the remaining ITO film 8 functionsas a protective film thus prevent ing the glass substrate SUB from beingshaved off.

Further, in forming the cutout portion UC in the common signal line CL,for example, as shown in FIG. 29, it is desirable to form the cutoutportion UC such that the cutout portion UC divides the through hole TH2in two.

Here, the cutout portion UC of the common signal line CL may beconfigured such that the outer periphery AR of the opening end of thethrough hole TH2 remote from the glass substrate SUB intersects theouter periphery of the common signal line CL in the cutout portion UC.Accordingly, it is needless to say that a shape of the cutout portion UCin a plan view is not limited to the shape shown in FIG. 29 and FIG. 31and various shapes are applicable as a planar shape of the cutoutportion UC.

Further, although the explanation using drawings is omitted, by formingthe through hole TH3 which connects the bridge line BR and the commonconnection pad CP into a shape (constitution) shown in FIG. 27 and FIG.28, it is possible to prevent a conductive failure between the commonsignal line CL and the bridge line BR and a defect of an orientationfilm.

Embodiment 5

FIG. 30 and FIG. 31 are schematic views showing the schematicconstitution of an essential part of a liquid crystal display panel ofan embodiment 5 according to the present invention.

FIG. 30 is a schematic plan view showing the schematic constitution ofthe through hole in the embodiment 5. FIG. 31 is a schematiccross-section al view taken along a line N-N′ in FIG. 30.

The embodiment 1 to the embodiment 4 focus on the through hole formed inthe pixel region of the display region DA of the liquid crystal displaypanel (TFT substrate 1), and the constitution al example to which thepresent invention is applied is explained.

However, there may be a case in which the through hole is formed outsidethe display region DA on the TFT substrate 1. In the embodiment 5, aconstitution al example in which the present invention is applied to thethrough hole formed outside the display region DA is explained.

In the case in which the TFT substrate 1 adopts the constitution shownin FIG. 3 to FIG. 5, for example, as shown in FIG. 30 and FIG. 31, thecommon bus line 9 which electrically connects the plurality of commonsignal lines CL is provided outside the display region DA, and thecommon bus line 9 and the respective common signal lines CL areconnected with each other via the through holes TH4, TH5 using thecommon line 10.

Here, the common bus lines 9 are, for example, formed simultaneously ina step in which the video signal lines DL or the like are formed.Further, the common lines 10 are formed simultaneously in the step inwhich the pixel electrodes PX are formed.

Further, in a region where the through hole TH4 which connects thecommon bus line 9 and the common line 10 with each other is formed, thestepped-portion forming layer MR explained in the embodiment 1 isformed, and the outer periphery of the opening end of through hole TH4remote from the glass substrate SUB passes through the region where thestepped-portion forming layer MR is interposed and the region where thestepped-portion forming layer MR is not interposed during one turn ofthe outer periphery. Here, the stepped-portion forming layers MR aresimultaneously formed in a step in which the semiconductor layers suchas channel layers SC of the TFT elements are formed. Due to such aconstitution, at a portion where a distance from the surface of theglass substrate SUB changes formed on the outer periphery of the openingend of the through hole TH4 remote from the glass substrate SUB, theresist material or the resin material in a liquid form can easily enterthe recessed portion formed in the through hole portion. Accordingly, itis possible to prevent a conductive failure between the common bus line9 and the common line 10 and a defect of an orientation film.

Further, in a region where the through hole TH5 which connects thecommon signal line CL and the common line 10 with each other is formed,as explained in the embodiment 4, the cutout portion UC is formed in thecommon signal line CL, and the outer periphery of the opening end ofthrough hole TH5 remote from the glass substrate SUB passes through aregion where the common signal line CL is interposed and a region wherethe common signal line CL is not interposed during one turn of the outerperiphery. Due to such a constitution, at a portion where a distancefrom the surface of the glass substrate SUB changes formed on the outerperiphery of the opening end of the through hole TH5 remote from theglass substrate SUB, the resist material or the resin material in aliquid form can easily enter the recessed portion formed in the throughhole portion. Accordingly, it is possible to prevent a conductivefailure between the common signal line CL and the common line 10 and adefect of an orientation film.

Here, in the region where the through hole TH5 which connects the commonsignal line CL and the common line 10 with each other is formed, forexample, as shown in FIG. 31, it is desirable that the ITO film 8 isinterposed between the common signal line CL and the glass substrate SUBand the cutout portion UC of the common signal line CL is formed of onlythe conductive film which is used for forming the scanning signal lineGL and the like. Due to such a constitution, when the through hole TH5is formed in the first insulation layer PAS1 and the second insulationlayer PAS2, the remaining ITO film 8 functions as a protective film thusprevent ing the glass substrate SUB from being shaved off in the cutoutportion UC.

FIG. 32 is a schematic cross-section al view for explaining amodification of the through hole in the embodiment 5. Here, FIG. 32 is across-section al view corresponding to a cross section taken along aline N-N′ in FIG. 30.

In the region where the through hole TH5 which connects the commonsignal line CL and the common line 10 with each other is formed on theTFT substrate 1 of the embodiment 5, for example, as shown in FIG. 31,it is desirable that the ITO film 8 is interposed between the commonsignal line CL and the glass substrate SUB. However, it is needless tosay that the present invention is not limited to such a constitutionand, for example, as shown in FIG. 32, the ITO film 8 may not beinterposed between the common signal line CL and the glass substrateSUB.

Further, in the embodiment 5, the TFT substrate 1 in which one pixel ofthe display region DA adopts the constitution shown in FIG. 3 to FIG. 5is exemplified. However, also with respect to a substrate TFT in whichone pixel of the display region DA adopts the constitution other thanthe above-mentioned constitution, holding capacitive lines may bearranged in parallel to the respective scanning signal lines GL and, therespective holding capacitive lines may be connected with each otherusing the common line 10 outside the display region DA. In this case,the common electrode CT is formed on another layer or on the countersubstrate and hence, the TFT substrate may be, as shown in FIG. 32,configured such that the ITO film 8 is not interposed between theholding capacitive line and the glass substrate SUB.

Here, in the embodiment 5, in a region where the through hole TH4 whichconnects the common bus line 9 and the common line 10 with each other isformed, the stepped-portion forming layer MR which is constituted of thesemiconductor layer and is simultaneously formed with the semiconductorlayer such as the channel layer SC of the TFT element is formed.However, it is needless to say that the stepped-portion forming layer MRis not limited to such a constitution, and the stepped-portion forminglayer MR may be simultaneously formed with the scanning signal lines GL.Further, it is needless to say that instead of forming thestepped-portion forming layer MR, the cutout portion UC may be formed inthe common bus line 9, for example.

Further, also with respect to the region where the through hole TH5which connects the common signal line CL and the common line 10 witheach other is formed, it is needless to say that instead of forming thecutout portion UC, for example, the stepped-portion forming layer MRsuch as the channel layer SC of the TFT element explained in conjunctionwith the embodiment 3 which is constituted of the semiconductor layerand is simultaneously formed with the semiconductor layer may be formed.

Although the present invention has been specifically explained inconjunction with the embodiment heretofore, it is needless to say thatthe present invention is not limited to the above-mentioned embodimentand various modifications are conceivable without departing from thegist of the present invention.

For example, in the embodiment 1 to the embodiment 5, the case in whichone pixel adopts the constitution shown in FIG. 3 to FIG. 5 has beenexplained. However, it is needless to say that the present invention isnot limited to such a constitution, and the present invention isapplicable to a through hole which connects two conductive layers on aTFT substrate having the convention ally known various constitutions.

Further, the embodiment 1 to the embodiment 5 have been explained bytaking the TFT substrate used in the liquid crystal display panel as anexample. However, the present invention is not limited to such anexample, and it is needless to say that the present invention isapplicable to a through hole which connects two conductive layers in adisplay panel including a substrate which has the substantially equalconstitution as the TFT substrate used in the liquid crystal displaypanel. That is, the present invention is not limited to the liquidcrystal display panel, and is also applicable to a self-luminescent typedisplay panel using a PDP (Plasma Display Panel) or an organic EL(Electro Luminescence) display panel, for example.

1. A display device comprising: a pair of substrates which is formed ofa transparent member; a first conductive layer which is formed on one ofthe substrates; a second conductive layer which is formed on a liquidcrystal side of the first conductive layer by way of an intermediatelayer which includes at least one insulation layer; and an openingportion formed in the intermediate layer, wherein out of opening ends ofthe opening portion, an outer periphery of the opening end on the liquidcrystal side has a distance thereof from the substrate changed one timeor more during one turn of the outer periphery.
 2. A display deviceaccording to claim 1, wherein the first conductive layer and the secondconductive layer are electrically connected with each other via theopening portion.
 3. A display device comprising: a pair of substrateswhich is formed of a transparent member; a first conductive layer whichis formed on one of the substrates; a second conductive layer which isformed on a liquid crystal side of the first conductive layer by way ofan intermediate layer which includes at least one insulation layer; andan opening portion formed in the intermediate layer such that the secondconductive layer is exposed, wherein the first conductive layer isformed to cover the opening portion, and an opening end of the openingportion is formed such that a distance between the opening end onanother substrate side and the substrate is set at least in two modes.4. A display device according to claim 3, wherein an outer periphery ofthe opening end on another substrate side passes through a region wherea semiconductor layer is interposed between the opening end and thesubstrate and a region where a semiconductor layer is not interposedbetween the opening end and the substrate.
 5. A display device accordingto claim 4, wherein the semiconductor layer is interposed between thesecond conductive layer and the substrate.
 6. A display device accordingto claim 4, wherein the intermediate layer includes two insulationfilms, and the semiconductor layer is interposed between two insulationlayers.
 7. A display device comprising: a pair of substrates which isadhered to each other by way of liquid crystal; a first conductive layerwhich is formed on one of the substrates; a second conductive layerwhich is formed on a liquid crystal side of the first conductive layerby way of an intermediate layer which includes at least one insulationlayer, and an opening portion formed in the intermediate layer such thatthe second conductive layer is exposed, wherein the first conductivelayer is formed to be electrically connected with the second conductivelayer by way of the opening portion, and a stepped-portion forming layeris formed on a portion between an opening end of the opening portion andthe substrate.
 8. A display device according to claim 7, wherein thestepped-portion forming layer is formed between the second conductivelayer and the substrate.
 9. A display device according to claim 8,wherein the stepped-portion forming layer is formed in a semicircularshape and a portion of the stepped-portion forming layer is overlappedwith a portion of the opening end.
 10. A display device according toclaim 8, wherein the stepped-portion forming layer is formed in arectangular shape and a portion of the stepped-portion forming layer isoverlapped with a portion of the opening end.
 11. A display deviceaccording to claim 8, wherein the stepped-portion forming layer isformed in a cruciform shape and a portion of the stepped-portion forminglayer is overlapped with a portion of the opening end.
 12. A displaydevice according to claim 8, wherein the stepped-portion forming layeris formed in a rectangular shape and a plurality of stepped-portionforming layers are arranged at positions where the stepped-portionforming layers are overlapped with the opening end.
 13. A display deviceaccording to claim 7, wherein the intermediate layer is constituted oftwo insulation layers and the stepped-portion forming layer isinterposed between the insulation layers and is formed at a positionwhere the stepped-portion forming layer is brought into contact with aportion of the opening portion.
 14. A display device according to claim13, wherein a plurality of stepped-portion forming layers are formed ina periphery of the opening portion.
 15. A display device comprising: apair of substrates which is adhered to each other by way of liquidcrystal; a first conductive layer which is formed on one of thesubstrates; a second conductive layer which is formed on a liquidcrystal side of the first conductive layer by way of an intermediatelayer which includes at least one insulation layer, and an openingportion formed in the intermediate layer such that the second conductivelayer is exposed, wherein the first conductive layer is formed to beelectrically connected with the second conductive layer by way of theopening portion, and a cutout portion is formed in the second conductivelayer at a position where the second conductive layer is overlapped withthe opening portion.
 16. A display device according to claim 13, whereinthe first conductive layer is connected with a switching element and thesecond conductive layer is a pixel electrode.
 17. A display deviceaccording to claim 13, wherein the second conductive layer is a counterelectrode, and the first conductive layer is a common line which isconnected to a common signal line which supplies an electric signal tothe counter electrode.